This application claims the priority of Korean Patent Application No. 2002-32523, filed Jun. 11, 2002 in the Korean Intellectual Property Office, the contents of which is incorporated herein in its entirety by reference.
1. Field of the Invention
The present invention relates to the generation of traffic in nodes coupled to a bus, and more particularly, to an apparatus and a method for generating distributed traffic in nodes coupled to a bus that supports hot plugging.
2. Description of the Related Art
Hot plugging is a method for connecting a node to a bus that does not require a complex identification process so that the node can be used immediately after being connected to the bus. To this end, a read transaction, by which a node accesses the other nodes connected to a bus and reads information on the other nodes from configuration ROMs of the other nodes, is necessary. Buses that support hot plugging include an IEEE 1394 bus, which is a digital interface standard for transmitting and receiving data between digital multimedia devices in real time.
Since the IEEE 1394 bus transmits data at a high speed, the IEEE 1394 bus processes real time data and asynchronous data simultaneously. In addition, according to the IEEE 1394 standard, low speed equipment and high-speed equipment may be used in the same network environment, so that the IEEE 1394 standard can comprehensively connect electronic home appliances, computers, and peripheral devices. Applications using the IEEE 1394 standard include the construction of home multimedia, and the production of a video having broadcast image quality by using a personal computer.
In the related art, a node denotes a device connected to a bus, and performs hot plugging. The node may be a complete product, such as a camcorder, or a component installed in a complete product.
When a bus reset occurs due to the connection of a new node to a conventional bus configured for hot plugging, each node connected to the bus tries to read information from the configuration ROMs of the other nodes and identify information on the other nodes according to a fixed order, as described with reference to FIGS. 1 and 2.
FIG. 1 is a block diagram illustrating nodes connected to a bus that supplies hot plugging in the related art. Here, N nodes (i.e., a first node 110 through an Nth node 170) are connected to a bus 180.
FIG. 2 illustrates the generation of a read transaction in which each node reads information on the other nodes in response to a bus reset. Here, four nodes (i.e., a first node 110 through a fourth node 140) are illustrated. When a bus reset occurs, each node tries to read information on the other nodes within a bus according to a fixed order so that read transactions are generated in the order of the node ID numbers (i.e., 1, 2, 3, . . . , N). Accordingly, as shown in FIG. 2, the second node 120 through the fourth node 140 try to read information on the first node 110. Thereafter, the first, third and fourth nodes 110, 130, and 140, respectively, try to read information on the second node 120. The nodes access the other nodes according to the fixed order, thereby generating traffic in the bus.
Therefore, every node accesses all of the other nodes in the order of the node ID numbers, so that traffic is concentrated on one node at an initial state of a bus reset, which causes serious delay in processing the nodes. After the delay in processing one node is resolved, the traffic is concentrated on the next node. Accordingly, the bus becomes stable and application operations can be performed only after the traffic has been concentrated on every node.